Implement shadow for UserManager#getMainUser

Not having the implementation causes B&R robolectric tests fail with a NPE.

Bug: 263981306
Test: atest BackupFrameworksServicesRoboTests
Change-Id: I47bf7ba42cf3bd23e472f8c9a21e4e657053ad42

1 files changed, 7 insertions, 0 deletions

diff --git a/services/robotests/src/com/android/server/testing/shadows/ShadowUserManager.java b/services/robotests/src/com/android/server/testing/shadows/ShadowUserManager.java
index a9e4ee521f90..16ba21067a62 100644
--- a/services/robotests/src/com/android/server/testing/shadows/ShadowUserManager.java
+++ b/services/robotests/src/com/android/server/testing/shadows/ShadowUserManager.java
@@ -18,6 +18,7 @@ package com.android.server.testing.shadows;
 
 import android.annotation.NonNull;
 import android.annotation.UserIdInt;
+import android.os.UserHandle;
 import android.os.UserManager;
 
 import org.robolectric.annotation.Implementation;
@@ -50,6 +51,12 @@ public class ShadowUserManager extends org.robolectric.shadows.ShadowUserManager
         return profileIds.get(userId).stream().mapToInt(Number::intValue).toArray();
     }
 
+    /** @see UserManager#getMainUser() */
+    @Implementation
+    public UserHandle getMainUser() {
+        return null;
+    }
+
     /** Add a collection of profile IDs, all within the same profile group. */
     public void addProfileIds(@UserIdInt int... userIds) {
         final Set<Integer> profileGroup = new HashSet<>();